1. Technical Field
The present invention relates to a multilayer inductor, and more particularly, to a multilayer inductor including a coil portion formed by multi-layering a plurality of body sheets on which an internal electrode is printed, and a method of manufacturing the same.
2. Description of the Related Art
A multilayer inductor is mainly used in a power circuit such as a DC-DC converter of a portable device. In this regard, research has been conducted on miniaturization, a high current, low DC resistance, or the like of multilayer inductors. Recently, due to the development of high frequency and miniaturization of a DC-DC converter, multilayer inductors have been increasingly used instead of conventional wound choke coils.
However, in a structure such as a multilayer inductor in which a body sheet formed of ferrite and an internal electrode are integrated with each other, internal stress is generated due to a thermal expansion coefficient difference between the body sheet and the internal electrode during sintering and cooling processes of manufacturing processes.
Since ferrite has magnetostrictive properties, the body sheet formed of ferrite is partially magnetized due to internal stress. Since an electron spin is fixed in a magnetized portion of the body sheet, a direction of the spin direction is not changed when an alternating current (AC) is supplied to the body sheet. Thus, permeability with respect to a magnetic field is reduced, thereby reducing inductance.
In addition, recently, since electronic components have been rapidly miniaturized, a volume ratio of an internal electrode to an electronic component such as a multilayer inductor has increased. Accordingly, internal stress is increased and inductance is seriously reduced due to the internal stress.